1. Field of the Invention
The present invention relates to an apparatus for measuring biological information and an earphone incorporating the apparatus having a sensor for measuring biological information by contact with a portion of a user's body.
2. Description of the Related Art
Measurement of biological information obtained from blood streams of a human body, such as a pulse rate, a number of heartbeats or the like, is performed using a variety of conventional devices of a variety of shapes or sizes, often miniaturized in a portable size or incorporated into other products.
For example, a measuring apparatus is provided in which a pulse sensor is installed within a wristwatch. When a user touches the pulse sensor using an inner surface of his/her fingertip, the pulse sensor optically detects a pulse count, and the pulse rate is displayed of the wristwatch.
The conventional apparatus for measuring the biological information as described above will typically use an electrocardiogram (ECG) sensor designed to measure the pulse rate by detecting signals using a multi-polar electrode. Further, a photo sensor has been disclosed to measure the biological information that irradiates light onto a skin surface of the user's body via a Light Emitting Diode (LED) and detects reflected light, observing scattering of light within the user's body via a Photo Diode (PD).
WO/2005/034742, the contents of which are incorporated herein by reference, is an example of a conventional apparatus for measuring the biological information. When this apparatus is used as a sensor for measuring the pulse rate using a transmission-type photo sensor applied to an earlobe, the sensor is adapted to compress the earlobe using pincers, that typically include two arms, a pivot and a spring.
However, the conventional ECG sensor needs to employ an electrode made from a conductive material or a special pad on which a high viscosity material, such as a gel, is applied. In addition, in order to perform a test while the user is exercising, the conventional ECG sensor must be installed on the user's body in a location, such as the chest, where muscles move. Further, it is difficult to obtain the number of heartbeats due to the disturbance of the ECG signals by the electromyogram (EGM) signal.
Special clothing, such as a bio-shirt, has been developed for use when tests are performed during exercise. However, use of such special clothing is inconvenient.
In order to solve the drawbacks described above, studies have been published for miniaturizing measuring devices for collecting biological information. As a result, an apparatus which can be mounted on an earphone using the structure of the user's ear has been developed.
When the apparatus for measuring the biological information is installed on the earphone, the apparatus adopts a measuring method to check the biological information with a transmission-type sensor positioned in an earflap of the user. However, such apparatus has drawbacks in that a significant amount of noise is generated by relative movement of the earphone against the user's skull. However, this relative movement is difficult to prevent due to the physical proximity of the earlobe to the skull and the weight of the earphone.
To solve the problems caused by the relative movement due to the weight of the earphone as described above, a lightweight chip of a sensor part is separated from the apparatus when the apparatus is in use. However, such construction is inconvenient in that the user must additionally care for the lightweight chip. A method to mount the chip in the earlobe of the user has also been proposed, but is structurally complicated due to its construction using a heavy earphone and an additional chip, making transport of the apparatus inconvenient.
As another way of solving the above drawbacks, an apparatus is provided in which the sensor part is completely inserted in the user's ear. Such apparatus, however, has disadvantages in that the user cannot listen to music because the apparatus interferes with an earphone function.
The above-described pincer-type apparatus is inconvenient to use since the spring force will vary depending on thickness and length of a user's earlobe, and further it is very difficult to obtain exact measurements.
Moreover, more space is needed due to the configuration of the pincer-type, and there is a practical inconvenience for the user because opening operations of the pincers for inserting the sensor part are totally contradicted with operations for inserting the earphone, when the apparatus is incorporated with the earphone.
Hence, there is a need for an apparatus capable that accurately measures exact biological information by elimination of the pressure difference caused by thickness and length variations in user earlobes, allowing the sensor to contact the earlobe with uniform pressure.